What is the easiest way to simulate trampoline?
Speaking to trampoline effect (simple one) ...


falling object with two keyframes (start / end Z position) with Dynamic Effect  Elastic (T) set in Graph Editor with first keyframe selected
"trampoline" worked better for me with Soft Body sim (Mass zero, Goal > Strength 1)




To protect object from penetration try for object Collision > Outer Thickness increase value a bit or for "trampoline" increase Solver > Step Size.